AKNO Energy: renewable energy for the construction sector

11 January 2019

What is renewable energy?

When we talk about energyespecially now that environmental sensitivity is widespread at every level and, despite some resistance, is influencing economic and industrial choices, we often hear about renewable energy sources. This definition is not entirely specific, even though it is widely used. Therefore, in order to define it better, it seems right to pause for a moment to talk about what AKNO Energy has developed in this sector.

To produce energy, it is possible to consume resources that exist in nature in limited quantities and that can be replaced only after processes that are too long to be considered from an economic and technical point of view. Resources that are defined as “non-renewable“, include petrol, coalnatural gas, uranium and, in general, all fuels which are not replaced by any natural process once burned.

In contrast, all those energy sources that nature continually makes available are called “renewable” and will not be exhausted, at least from the point of view of an engineering timescale. Plants that produce energy using the sun’s rayswindwavetidalgeothermal (heat from the deep layers of the Earth’s crust) and hydropower are all examples of renewable energy sources.

Renewable sources and environmental balance

There are also some energy sources that cannot, strictly speaking, be classified as renewable, but which are often associated with them. These are the cases in which energy is produced using something that constitutes waste coming from other human activities and therefore is continuously available (not from nature, but because of human activities). For example, non-differentiable urban waste can be used to produce energy in a waste-to-energy plant, or to burn off the residues of some industrial processes or to obtain biogas from the fermentation of farm by-products and some agricultural activities.

A more modern and precise method to assess the benefits of an energy source from an environmental point of view is to estimate the difference between the negative impact produced using that particular energy source and the impact caused by its alternative use. With this system, called environmental balance, we can assess, for example, the difference in COemissions between the production and combustion of biogas obtained from farm manure compared to its disposal as waste.

In the same way we can compare the environmental disadvantage from the damage done by covering an area with solar panels to the advantage in terms of energy production without polluting emissions.

Following this criterion and the principles of the Leadership in Energy and Environmental Design (LEED) protocolAKNO has decided to focus on two sources of clean energy for its business park: the production of electricity with photovoltaics and biogas plants.

Monocrystalline or polycrystalline?

Photovoltaic plants use a particular property of pure silicon crystals, combined in an appropriate way, to generate an electric voltage when they are hit by the sun’s rays.

Therefore, it is a system for producing totally renewable electricity, even if from the point of view of environmental balance it has some negative aspects.

The solar panel, in fact, is a fixed structure that prevents sunlight from reaching the underlying soil. Thus, it precludes any agricultural use, constituting a cause of the so-called “land consumption” phenomenon.

For this reason, a low environmental impact photovoltaic system must use roof surfaces, just like the roofs of AKNO business parks structures and warehouses.

In particular, AKNO Energy has chosen to use polycrystalline silicon panels, i.e. those in which the different silicon crystals that make up the cells have different orientations at a microscopic level.

Indeed, this type of panel ensures good performance at any ambient temperature. On the other hand, despite having a higher yield per square meter of irradiated surface during their best operating conditions, monocrystalline panels lose much of their effectiveness on the hottest days, when the ambient temperature becomes high.

Our photovoltaic systems, positioned on the roofs of the buildings we construct, generally have a yield of between 12 and 14% and significantly contribute to financial savings for the entire structure as they can independently produce a significant percentage of the electrical energy it needs.

Biogas plants

It often happens that our business parks are located close to some areas where zoo-technical and agricultural activities develop: just think of the Po Valley where the industrial and agricultural sectors are tightly connected.

This close connection, as we will see, allows us to have the raw material needed to run our biogas plants.

Indeed, to produce biogas it is necessary to collect waste from farms and agricultural processing in specific structures, called digesters, to allow particular bacteria to carry out a process called anaerobic digestion that results in a mixture of combustible gases.

This mixture takes the generic name of biogas and is mainly composed of methane, like natural gas that is extracted from the subsoil, but it also contains some non-combustible substances.

Therefore, considering the same volume, biogas capacity to generate heat from combustion is almost half that of natural gas (23 MJ / m3against 40 MJ / m3). However, this disadvantage is amply compensated for, both in terms of environmental impact and in terms of total costs, because it is possible to produce fuel directly on-site employing raw waste material.

Biogas combustion, which occurs in boilers controlled by an automatic system that limits polluting emissions as much as possible, produces the necessary heat both to maintain the aerobic digestion process of new material being processed and to heat the buildings it is connected to.

The carbon dioxide emissions of the entire process are certainly lower than those that would be produced by disposing of the organic waste used in landfills, not to mention the savings we obtain, in environmental terms, by avoiding gas extraction from the subsoil.

This is another way in which AKNO Energy is proud to contribute to the fight against climate change that can be achieved by reducing CO2 emissions.